This invention relates to a method and kit for measuring the effectiveness of bronchodilators on an individual patient. The invention relates more particularly to a method and kit for providing a quantitative comparison, so that a physician can select the most effective treatment for a patient.
Physicians have for many years used spirometers to test for reversible airway diseases such as asthma. In fact, spirometry is considered to be the single most useful test for evaluating asthma. Physicians have also used spirometers for bronchodilator studies. And, in conducting such studies, the physician or technician has a patient exhale before and after inhaling a bronchodilator from a metered-dose aerosol generator. And, the patient is instructed to hold the inspired volume of aerosol for at least several seconds before exhalation.
In conducting spirometer tests, the spirometer indicates the volume, flow, and ventilation capacities of the respiratory system. For example, the spirometer is commonly used to measure the following:
Vital Capacity (VC); the maximum volume of air exhaled from the point of maximum inspiration;
Forced Vital Capacity (FCV); is the vital capacity performed with a maximally forced expiratory effort;
Timed Forced Expiratory Volume (FEV.sub.T); is the volume of air exhaled in the specified time during the performance of the forced vital capacity;
Forced Expiratory Volume I (FEV.sub.I); is the volume of air exhaled during the first second of the FVC; and
Peak Expiratory Flow (PEF); is the maximum rate of flow exhaled during a forced expiration of the lungs.
In the past it has been generally assumed that known bronchodilators are statistically equivalent. Accordingly, many physicians consider that an individual patient's lungs react differently to treatment with different bronchodilators. Other physicians have resorted to trial and error methods for determining which bronchodilator is best for which patient. Prior studies also assumed that bronchodilators should be withheld from the patient for a period of at least 6 or 8-12 hours prior to the test. See, for example, Pulmonary Diseases-Focus on Clinical Diagnosis, pp. 50 and 222, Medical Examination Publishing Co., Inc. 1983.
It has now been found that individual patients react differently to treatment with different bronchodilators. It has also been found that a series of tests can be conducted in a relatively short period of time to obtain and verify quantitative date which will enable a physician to prescribe a preferred treatment for a particular patient.